Magisk Overlayfs

• Make system partition (/system, /vendor, /product, /system_ext) become read-write. Important: you can only modify content in subdirectories of partitions. It's known that cover entire partitions with overlayfs will cause some problem.
• Use /data as upperdir for overlayfs to store modifications. All modifications to overlayfs partition will not be made directly, but will be stored in upperdir, so it is easy to revert.
• Support Magisk version 23.0+ and latest version of KernelSU

If you are interested in OverlayFS, you can read documentation at https://docs.kernel.org/filesystems/overlayfs.html

If you can't modify system files with MT File Manager, try using Material Files instead!

Build

There is two way:

• Fork this repo and run github actions
• Run bash build.sh (On Linux/WSL)

Change OverlayFS mode

• OverlayFS is mounted as read-only by default

• Configure overlayfs mode in /data/adb/modules(_update)/magisk_overlayfs/mode.sh to change mode of OverlayFS

Read-write mode of overlayfs will cause baseband on some devices stop working

# 0 - read-only but can still remount as read-write
# 1 - read-write default
# 2 - read-only locked (cannot remount as read-write)

export OVERLAY_MODE=2

• OverlayFS upper loop device will be setup at /dev/block/overlayfs_loop
• On Magisk, OverlayFS upper loop are mounted at $(magisk --path)/overlayfs_mnt. You can make modifications through this path to make changes to overlayfs mounted in system.

Overlayfs-based Magisk module

• If you want to use overlayfs mount for your module, add these line to the end of customize.sh

OVERLAY_IMAGE_EXTRA=0     # number of kb need to be added to overlay.img
OVERLAY_IMAGE_SHRINK=true # shrink overlay.img or not?
INCLUDE_MAGIC_MOUNT=false # enable legacy Magisk mount or not when Magisk_OverlayFS is disabled

if [ -f "/data/adb/modules/magisk_overlayfs/util_functions.sh" ] && \
    /data/adb/modules/magisk_overlayfs/overlayfs_system --test; then
  ui_print "- Add support for overlayfs"
  . /data/adb/modules/magisk_overlayfs/util_functions.sh
  support_overlayfs
  rm -rf "$MODPATH"/system
fi

• We mounted your overlay modules at $MAGISKTMP/overlayfs_modules so you can modify it without having to manually mount it

Bugreport

• Please include /cache/overlayfs.log

Reset overlayfs

• Remove /data/adb/overlay and reinstall module

Without Magisk

• Possible to test:

mkdir -p /data/overlayfs
./overlayfs_system /data/overlayfs

Source code

• http://github.com/HuskyDG/Magisk_OverlayFS